A 24-year-old woman presents with a severely painful, red, light-sensitive right eye that started yesterday and worsened overnight. Vision in that eye is blurred. There is a yellowish discharge. She wears monthly soft contact lenses and admits she has slept in them for three nights in a row during exams, topping up the case with tap water. She has no previous eye disease.
Examination Findings
Visual acuity: right 6/60, left 6/6. Right eye: marked injection, a 3 mm central corneal ulcer with dense white stromal infiltrate and an overlying epithelial defect that stains with fluorescein; 1.5 mm hypopyon in the anterior chamber; lid swelling. Corneal sensation is present. She slept in her monthly soft lenses for three nights running and rinsed the case with tap water. No trauma. Left eye is normal.
Investigations
Corneal scraping for Gram stain and culture is taken before antibiotics are started — the key investigation that later tailors therapy. The contact lens and case are also cultured when available. Anterior-segment photography documents the ulcer size. Intraocular pressure is checked once the acute phase settles.
Questions to Think About
- Why must the corneal scraping come before the first antibiotic drop?
- What two lens habits caused this, and what is the safe alternative?
- Why is a hypopyon an emergency marker?
Diagnosis
Bacterial keratitis (corneal ulcer) with hypopyon in an overnight contact-lens wearer, right eye.
Reasoning
Reasoning: An acutely painful red eye with a fluorescein-staining corneal ulcer, dense stromal infiltrate and hypopyon in an overnight lens wearer is bacterial keratitis. The hypopyon — sterile pus layered in the anterior chamber — signals a severe inflammatory response to the infection. Overnight wear deprives the cornea of oxygen and the tap-water rinsing seeds the case with organisms; together they are the classic history. Acanthamoeba is considered because of the water exposure and severe pain, but the frank suppuration favours bacteria first. Diagnosis: bacterial keratitis with hypopyon, contact-lens related. Management: typical management is urgent ophthalmic care with corneal scrapings for culture before intensive topical antibiotics per local protocol, daily monitoring of ulcer size, and complete cessation of lens wear with disposal of lenses and case. She learns the non-negotiable rules: never sleep in lenses unless specifically prescribed for it, never use tap water on lenses or cases, and any painful red eye in a lens wearer is an emergency.
Differential Diagnosis
- Acanthamoeba keratitis — considered: contact-lens wear with severe pain fits, but the rapid onset with frank pus and hypopyon favours bacterial; still, a poor response to antibacterials would prompt a rethink.
- Herpetic keratitis — ruled out: no dendritic pattern, no reduced corneal sensation, and the picture is a suppurative ulcer with hypopyon rather than a branching epithelial lesion.
- Sterile contact-lens infiltrate — ruled out: the epithelial defect with dense stromal infiltrate, anterior chamber reaction and hypopyon mark true infection, not a sterile event.
Management
Typical management includes urgent referral to ophthalmology, corneal scrapings for microbiology, and intensive topical antibiotics (fortified or high-concentration fluoroquinolone per local protocol) with close daily review. Contact-lens wear stops completely, the case and lenses are discarded, and she is taught safe lens hygiene for the future. If the ulcer worsens or the culture suggests an atypical organism, therapy is adjusted per local protocol.
Key Learning Points
- Sleeping in lenses and tap-water rinsing are the two great modifiable risks for contact-lens keratitis.
- A hypopyon means severe infection — this is an emergency, not a ‘red eye’ for the pharmacy.
- Corneal scrapings must come before the first antibiotic drop; after that the culture is compromised.
- Never patch an infected cornea and never use steroid drops in suspected bacterial keratitis.
- Ulcer size and location (central versus peripheral) drive the visual prognosis.
Red Flags
- Hypopyon or a large central ulcer — sight-threatening infection needing same-day ophthalmology.
- Pain out of proportion with a ring infiltrate — think acanthamoeba, especially with tap-water exposure.
- Worsening despite intensive antibiotics — reconsider the organism and the diagnosis.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.